We have
#\frac{-4+5i}{-1+6i}#
#=\frac{\sqrt{41}e^{i(\pi-\tan^{-1}(5/4))}}{\sqrt{37}e^{i(\pi-\tan^{-1}(6))}}#
#=\sqrt{\frac{41}{37}}(e^{i(\pi-\tan^{-1}(5/4))}e^{-i(\pi-\tan^{-1}(6))})#
#=\sqrt{\frac{41}{37}}(e^{i(\tan^{-1}(6)-\tan^{-1}(5/4))})#
#=\sqrt{\frac{41}{37}} e^{i\tan^{-1}(19/34)}#
#=\sqrt{\frac{41}{37}}(\cos(\tan^{-1}(19/34))+i\sin(\tan^{-1}(19/34)))#
#=\sqrt{\frac{41}{37}}(34/\sqrt1517+i19/\sqrt{1517})#
#=\sqrt{\frac{41}{37\times 1517}}(34+19i)#
#=1/37(34+19i)#